I taught myself to knit in the round with circular needles, and I love to use them! I actually bought an interchangeable kit, but only because I had a good coupon and got them for a pretty good price. I don't know that I would recommend spending a lot of money in case you don't like it.
With that said, I have played around with dpns a bit, but not too much to decide if I "like" them yet.
One thing I learned the hard way with knitting in the round was that garter stitch and stockinette stitch are reversed from knitting flat. In fact, my first project was a hat that was supposed to be stockinette stitch (which is knit every row when knitting in the round)...needless to say, I knitted it like I was knitting flat.
It was ok, my husband said he liked the hat I made for him anyway.
Good luck with your first project!